A conventional, fast pattern matching process for a template image and an image in a search region is disclosed in, for example, Japanese Unexamined Patent Publication No. Hei 5-298451, Japanese Examined Patent Publication No. Sho 62-11389, and Japanese Unexamined Patent Publication No. Sho 62-249293. In the example disclosed in Japanese Unexamined Patent Publication No. Hei 5-298451, Hadamard's transformation is employed for the pattern matching. To calculate a Hadamard factor, a Hadamard factor that was previously obtained is employed and calculations are performed only for portions that have changed, so as to reduce the number of calculations required and to provide fast processing.
In the example disclosed in Japanese Examined Patent Publication No. Sho 62-11389, a pattern recognition technique is employed whereby the outline of the elements included in a pattern is traced to acquire pattern information. One point is extracted for each element while at the same time pattern linkage is detected, so that a start point for tracing can be detected within a short period of time.
In the example disclosed in Japanese Unexamined Patent Publication No. Sho 62-249293, a technique is employed whereby image data are recognized by using a template. The degree to which the run-length coding data for the image data match a template comprising run-length data is measured directly, so that a process whereby run-length coding data are decoded to obtain binary image data is eliminated, and fast processing can be performed.
Other conventional examples resembling pattern matching are disclosed in Japanese Unexamined Patent Publication Nos. Hei 2-68682, Hei 4-337889, Hei 8-30784 and Hei 8-54221.